Re: How come Ada isn't more popular?

[<adaworks@sbcglobal.net>]

"kevin cline" <kevin.cline@gmail.com> wrote in message 
news:1169684558.876074.40530@s48g2000cws.googlegroups.com...
>
>
> On Jan 24, 10:14 am, <adawo...@sbcglobal.net> wrote:
>> "kevin cline" <kevin.cl...@gmail.com> wrote in message >
>> > Yes, I've read that article.  It would really be sad if Ada were not
>> > superior to C for a toy problem in embedded control system development,
>> > since Ada was designed specifically for that purpose.  But the point
>> > was that expressiveness drives programmers to new languages, and Ada
>> > isn't particularly expressive.It depends on what you want to express. 
>> > Expressiveness, like beauty,
>> is often "in the eye of the beholder."  For many software professionals,
>> the absence of curly-braces makes a language less expressive.  For
>> others, their presence is a problem.   For some, brevity is a sign of
>> expressiveness.  For others, ease of understanding on the part of a
>> reader is important to expressiveness.
>>
>> I do know a lot of languages, including many in the C family.  I have
>> programmed in COBOL, Fortran, PL/I, BASIC, Python, and many
>> others.   I teach a class in comparative programming languages.
>>
>> An important distinction to be made is expressibility versus expressiveness.
>> The fact that I can express a solution in Fortran that is better suited to 
>> being
>> expressed in COBOL does not mean that Fortran is expressive.   When
>> a solution is possible, that makes it expressible.  When the language is
>> designed to express such solutions, that makes it expressive -- for that
>> kind of problem.
>>
>> Languages evolve to become more expressive.  Fortran has evolved.  COBOL
>> has evolved.  Ada has evolved.  Even Java continues to evolve.  Some 
>> languages
>> seem not to evolve and remain stagnent.  PL/I comes to mind.   Some 
>> programmers
>> do not evolve, and they also become out-of-date.
>>
>> As languages evolve some tend to get better at being more directly 
>> expressiveof
>> a larger range of solutions.  Not all languages evolve well.   In my view, 
>> C++
>> has not become better with its most recent "improvements."
>>
>> Ada is expressive of a large number of solutions that are more difficult to
>> express in C or other languages.  However, the base language is not as
>> expressive as Perl for regular expressions.  That has required a separate
>> library unit.  It is not as directly expressive of mathematical solutions as
>> Fortran.  That too requires library units.    All the fundamental constructs
>> are in place to create powerful library units.
>
> Not as powerful as I would like, and definitely not as powerful as C++
> templates.

But safer than C++, overall.  And safer than C++ templates.

>Christopher Grein demonstrated this conclusively in his
> paper on modeling scientific units in Ada.  C++ templates allow the
> straightforward construction of a compile-time safe system of physical
> units, allowing arbitrary computations, while Ada's explicit
> instantiation model forced one to rely on run-time checking.
>
I have not read Christopher Grein's paper, and from what I know
of C++ and C++ templates, I am skeptical of the notion of it being
compile-time safe under any circumstances.   I suppose one could
write some very careful code to make that true, but the language
itself is not inherently safe.

I have not had the experience of having to rely on run-time checking
for templates.   In fact, my own experience of generics is that they
tend to enforce a great deal of checking at compile-time.  That being
said, C++ templates do allow more complex variations on genericity,
and that does not contribute to type-safe software.

The whole point of Ada is to allow the maximum amount of checking
at compile-time.   In fact, the point of the language design is to maximize
the amount of checking possible over the entire system as early in the
development as possible.   C++ does not support anything close to
that goal except in a few isolated places within the langauge design.
We would want to evaluate the language as a whole, not one or
two features.   We can compare C++ to Visual Basic and make
Visual Basic come out ahead.  We can compare Ada to COBOL
and make COBOL come out ahead.   In both cases, it will depend
on our criteria and what we decide to compare.

As to power.  With Ada you get more power, safely, than you do in
C++ or Java.   Empowering a language, while making it less safe
is not a good thing.   As for Grein's paper, which I will take the time
to read, it is my experience that one can make a case quite nicely
by stacking the evidence in a particular way.    I will try to find a
copy of the paper and make my own judgement about that.

Richard Riehle